To compare the risks of developing invasive squamous cell cervical cancer associated with screening intervals of 1, 2, and 3 years after a negative cervical smear.
We conducted a matched case-control study of invasive squamous cell cervical cancer patients (n= 482) diagnosed between 1983 and 1995 among long-term members of a large health maintenance organization. Controls were matched for age, length of membership, and race (n= 934). Screening interval was time between the last negative cervical smear and the case diagnosis date. The main outcome measure was the relative odds of invasive disease associated with 1-year, 2-year, and 3-year intervals.
The odds ratio for a 2-year versus a 1-year interval was 1.72 (95% confidence interval 1.12, 2.64,P= .013) and for a 3-year versus a 1-year interval was 2.06 (95% confidence interval 1.21, 3.50,P= .007). The odds ratio for a 3-year versus a 2-year interval was 1.20 (95% confidence interval 0.65, 2.21,P= .561). Controlling for ever having had an abnormal cervical smear or a previous consecutive negative smear did not substantially change these results.
In this large health plan, the relative risks of invasive squamous cell cervical cancer were significantly greater for 2-year and 3-year cervical cancer screening intervals compared with a 1-year interval, but not for a 3-year interval compared with a 2-year interval. Our findings need to be placed in the context of the low absolute risks of developing invasive cervical cancer during the first 3 years after a negative cervical smear before making policy recommendation. (Obstet Gynecol 2003; 101: 29-37. © 2003 by The American College of Obstetricians and Gynecologists.)
From the Department of Quality and Utilization and Division of Research, Kaiser Permanente Medical Care Program, Oakland, California; Division of Gynecologic Oncology, Kaiser Permanente Medical Care Program, Sacramento, California; Institute for Health and Aging, School of Nursing, and Departments of Obstetrics, Gynecology, & Reproductive Sciences and Epidemiology and Biostatistics, University of California, San Francisco, California.
RAH is currently affiliated with The Division of Cancer Control and Population Sciences, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
Noel S. Weiss, MD, Dr PH (University of Washington, Seattle, Washington), Joe V. Selby, MD (Division of Research, Kaiser Permanente Medical Care Program, Oakland, California), and Nicholas P. Jewell, PhD (University of California, Berkeley, California) provided extensive methodological consultation on the design and analysis of this study.
Funding for this project came from the Department of Quality and Utilization and from the Innovations Program of the Kaiser Permanente Medical Care Program, Oakland, California, Grant Numbers 950062 and 960032.
An abstract of this work was presented at the 2001 Annual Meeting of The American College of Obstetricians and Gynecologists and was awarded second place for original research.
Address reprint requests to: Marie Grisham Miller, PhD, 2331 Rancho del Lago Road, Martinez, CA 94553; E-mail: email@example.com.
Received February 22, 2002. Received in revised form April 29, 2002. Accepted May 2, 2002.